to setup
  ca
  setup-plotting
  cct 1
  [                                         ; create one turtle
    set color red
    set xcor (2 - screen-edge-x)                  ; set the turtle's initial position and heading
    set ycor 0
    set heading 0
    pd
  ]
end

to go
  every 0.05
  [
    ask turtles
    [
      fd (pi * (screen-edge-y - 2) / 180) * 2       ; move in circle
      rt 2
      if pcolor = color                             ; if we've come all the way around the circle
        [set color color + 10]
    ]
    do-plot                                                                         
  ]
end

;;plotting procedures -------------------

to setup-plotting
  set-current-plot "Turtle Positions"                                                    
  set-plot-y-range  (- screen-edge-y) screen-edge-y          ; set y range to graphics window size
end

to do-plot
  set-current-plot-pen "Xcor"
  plot xcor-of turtle 0            ; plot xcor -- there's only one turtle, so its id must be 0
  set-current-plot-pen "Ycor"
  plot ycor-of turtle 0            ; plot ycor -- ditto
end
@#$#@#$#@
GRAPHICS-WINDOW
321
10
697
407
30
30
6.0
1
10
1
1
1

CC-WINDOW
18
10
238
172
Command Center

BUTTON
256
23
311
56
NIL
setup
NIL
1
T
OBSERVER
T

BUTTON
257
68
312
101
go
go
T
1
T
OBSERVER
T

PLOT
8
193
308
392
Turtle Positions
Time
Position
0.0
100.0
-30.0
30.0
true
true
PENS
"Xcor" 1.0 0 -65536 true
"Ycor" 1.0 0 -16776961 true

@#$#@#$#@
WHAT IS IT?
-----------
This shows all of the code needed to set up a plot which will display two variables as the model runs.  In this case, the two variables are the x-coordinate and the y-coordinate of a turtle.
@#$#@#$#@
default
true
0
Polygon -7566196 true true 150 5 40 250 150 205 260 250

arrow
true
0
Polygon -7566196 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150

box
true
0
Polygon -7566196 true true 45 255 255 255 255 45 45 45

circle
true
0
Circle -7566196 true true 35 35 230

person
false
0
Circle -7566196 true true 155 20 63
Rectangle -7566196 true true 158 79 217 164
Polygon -7566196 true true 158 81 110 129 131 143 158 109 165 110
Polygon -7566196 true true 216 83 267 123 248 143 215 107
Polygon -7566196 true true 167 163 145 234 183 234 183 163
Polygon -7566196 true true 195 163 195 233 227 233 206 159

spacecraft
true
0
Polygon -7566196 true true 150 0 180 135 255 255 225 240 150 180 75 240 45 255 120 135

thin-arrow
true
0
Polygon -7566196 true true 150 0 0 150 120 150 120 293 180 293 180 150 300 150

truck-down
false
0
Polygon -7566196 true true 225 30 225 270 120 270 105 210 60 180 45 30 105 60 105 30
Polygon -8716033 true false 195 75 195 120 240 120 240 75
Polygon -8716033 true false 195 225 195 180 240 180 240 225

truck-left
false
0
Polygon -7566196 true true 120 135 225 135 225 210 75 210 75 165 105 165
Polygon -8716033 true false 90 210 105 225 120 210
Polygon -8716033 true false 180 210 195 225 210 210

truck-right
false
0
Polygon -7566196 true true 180 135 75 135 75 210 225 210 225 165 195 165
Polygon -8716033 true false 210 210 195 225 180 210
Polygon -8716033 true false 120 210 105 225 90 210

turtle
true
0
Polygon -7566196 true true 138 75 162 75 165 105 225 105 225 142 195 135 195 187 225 195 225 225 195 217 195 202 105 202 105 217 75 225 75 195 105 187 105 135 75 142 75 105 135 105

@#$#@#$#@
NetLogo 2.0beta4
@#$#@#$#@
setup
repeat 100 [ go wait 0.05 ]
@#$#@#$#@
@#$#@#$#@